Study of mosquito fauna in rice ecosystems around Hanoi, Northern Vietnam

Species of the Culex vishnui subgroup, Culex fuscocephala and Culex gelidus, which are known Japanese encephalitis (JE) vectors, are distributed in rice agroecosystems in Asian countries. Hence, although ecological studies of rice agroecosystems in northern Vietnam are necessary, very few integrated studies of breeding habitats of mosquitoes, including JE vectors, have been conducted. We carried out a field study and investigated the mosquito fauna in six rice production areas in northern Vietnam during the rainy and dry seasons of 2009. Mosquitoes and potential mosquito predators were collected from aquatic habitats by using larval dippers. We collected 1780 Culex individuals (including 254 Culex tritaeniorhynchus; 113 Culex vishnui, 58 Culex vishnui complex, consisting of Culex vishnui and Culex pseudovishnui; 12 Culex gelidus; 1 Culex bitaeniorhynchus; and 1 Culex fuscocephala), 148 Anopheles individuals (including 5 Anopheles vagus), 1 Mansonia annulifera, and 1 Mimomyia chamberlaini during the rainy season. During the dry season, we collected 176 Culex individuals (including 33 Culex vishnui, 24 Culex tritaeniorhynchus, 8 Culex vishnui complex, and 1 Culex gelidus) and 186 Anopheles individuals (including 9 Anopheles tessellatus, 2 Anopheles kochi, and 2 Anopheles barbumbrosus). We found mosquitoes in all aquatic habitats, namely, rice fields, ditches, ponds, wetlands, irrigation canals, and rice nurseries, and Culex tritaeniorhynchus and Culex vishnui complex were found in all the above six areas. Heteroptera such as Micronecta, Veliidae, and Pleidae were abundant and widely distributed in both the seasons. The abundance of mosquito larvae was higher in the rice fields, ditches, and ponds during the rainy season than during the dry season. Culex tritaeniorhynchus, Culex vishnui complex, Culex fuscocephala, and Culex gelidus were abundant in rice agroecosystems (rice fields, ditches, ponds, and wetlands) in northern Vietnam, and their abundance was high during the rainy season. These findings deepen our understanding of mosquito ecology and strengthen mosquito control strategies to be applied in rice ecosystems Vietnam in the future. (C) 2014 Elsevier B.V. All rights reserved.